How to Unclog a Plumbing Vent in Claremont, CA.

The quick method for unclogging a plumbing vent.

To unclog a plumbing vent, go up to the roof only if it is dry, low-pitched and you are comfortable there. Find the open pipe through the shingles, shine a flashlight down it, and pull out visible debris. Then run a garden hose down the pipe. If water backs up, feed a small drain snake in a foot at a time, and flush again.

If the pipe is clear but drains still gurgle, the problem is likely lower in the system. If the roof is steep, wet or high, skip the climb and call a plumber instead. No clogged vent is worth a fall.

What the vent does and why it clogs.

Every drain in a house needs air. When water runs down a pipe, it pushes air ahead of it and pulls air behind it. The vent system, which is a network of pipes that ends in an open stack on the roof, lets air move in and out so water flows smoothly and P-trap seals do not get sucked dry.

When the open end plugs, drains slow down or gurgle because air has nowhere to come from. The usual culprits are small and outdoor in origin.

• Leaves, pine needles and twigs falling into the stack.
• A bird nest or a dead animal.
• Tennis balls or toys knocked in by kids or squirrels.
• Ice or heavy debris in colder climates.
• Roofing materials or paint that partly cover the opening.

Safety before you climb.

A roof is the real danger in this job, not the plumbing. Work only on a dry day with no wind, and never alone. Wear shoes with grip, use a ladder that extends well above the roof edge, and have someone hold it at the bottom. If you feel any hesitation, stop.

Never lean on old, brittle roof tiles, and avoid stepping on a roof in the middle of the day when the surface is hot or slippery. Keep away from power lines near the roofline. If the vent is on a steep or two-story roof, hire a plumber. That is a normal call, not a failure.

Tools you actually need.

You can clear most vent clogs with ordinary supplies. Gather them before you go up so you are not climbing twice.

• A garden hose with an adjustable nozzle.
• A hand-crank drain snake of about 25 feet.
• A flashlight.
• Work gloves and eye protection.
• A small bucket or bag for debris.
• A long-handled grabber or tongs for visible objects.

Step by step: clearing a vent stack.

Clearing the vent from the roof.

1. 1

   Locate the stack.

   Look for the pipe poking through the roof, usually 3 or 4 inches across and often near the bathrooms or kitchen. There may be more than one.

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2. 2

   Look inside.

   Shine a flashlight down. Remove leaves, nests or objects you can reach with gloves or a grabber.

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3. 3

   Flush with the hose.

   Run water slowly down the pipe. If it drains steadily, the vent is open. If it rises or stalls, the blockage is deeper.

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4. 4

   Snake the pipe.

   Feed the snake down gently, turning the handle as you push. Stop when you feel resistance, work it back and forth, then pull it out and clean it.

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5. 5

   Flush again.

   Rinse the stack until water runs freely. Listen from inside the house to see if the gurgling has stopped.

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Check from the inside afterward.

Go back inside and run water at the fixture that gurgled worst. Flush the toilet, then run the shower and sink together. If the sounds are gone and the water drains quickly, the vent was the problem. If the gurgling returns, the clog may be in the drain line, not the vent.

A drain clog and a vent clog look alike from inside the house, which is why many people clear one and still have the other. If you want a clear answer on what is blocked, a plumber can run a camera down the line. Our drain cleaning service covers that kind of diagnosis.

When DIY is not the right move.

Some vent problems are beyond a hose and a snake. A pipe that is cracked, flattened or disconnected inside the attic cannot be fixed from the roof. A vent that was never installed correctly, or one that is too small or too far from the fixture, is a design problem that cleaning will not solve.

When a vent has to be rebuilt.

Sometimes the vent pipe itself needs work. A rotted connection, a missing vent after a remodel or a bathroom added without proper venting can all cause chronic slow drains. Fixing that means cutting in new pipe and tying it into the existing system, which is installation work, not cleaning.

If that sounds like your house, a licensed plumber can look at what was done before and recommend a fix. Our plumbing installation page explains how new and corrected piping is handled. The same goes for homes in Pomona and Montclair that were remodeled.

Why the clog may be below the house instead.

A vent can be perfectly clear while the drain it serves is full. Grease, hair, wipes and tree roots all clog horizontal lines. When the main line is partly blocked, you get the same gurgling and slow flow. The big clue is whether several fixtures act up at once and whether the toilet bubbles when you run the washing machine.

Preventing the next clog.

Vent clogs tend to repeat when the cause is nearby. A tree overhanging the roof drops needles and leaves into the opening. A vent without a proper cap collects debris, and an unscreened stack can attract nesting birds.

• Trim branches that drop debris near the stack.
• Check the vent opening twice a year, especially after storms.
• Ask a plumber about a vent cap that is allowed for your setup.
• Keep wipes and grease out of the drains.